Glass-like thermal transport in polycrystalline perovskite lithium-ion conductor Li _3/8 Sr _7/16 Hf _1/4 Ta _3/4 O ₃

Understanding the thermal properties of lithium-ion conductors is vital for optimizing heat dissipation and enhancing the overall performance, reliability, and safety of all-solid-state batteries. Here, we investigate the specific heat and thermal conductivity of Li_3/8Sr_7/16Hf_1/4Ta_3/4O₃ (LSHT), a promising perovskite-type lithium-ion conductor. We found that LSHT exhibits glass-like thermal behavior with a low thermal conductivity of 1.7 ± 0.5 W m^-1 K^-1 at room temperature, comparable to some amorphous materials yet distinct from typical crystalline perovskites. Our theoretical analysis indicates that diffusons contribute significantly to heat transfer within this highly disordered material. These findings provide crucial insights into thermal transport in LSHT, which are essential for effective thermal management in all-solid-state batteries utilizing this material.